Carbonic anhydrase activity in the trigeminal primary afferent neuronal cell bodies with peripheral axons innervating the mandibular molar tooth pulps of the rat.

Trigeminal primary afferent neuronal cell bodies were labeled with FITC-WGA retrogradely transported from the mandibular molar tooth pulp (tooth pulp) and the cutaneous branch of the mylohyoid nerve (cutaneous nerve) in the rat. Tissue sections were then incubated in Hansson's medium for histological demonstration of carbonic anhydrase (CA) activity. About 85% of primary neurons innervating the tooth pulp had medium to large cell bodies (greater than or equal to 300 microns 2 in cross-sectional area), while 77% of those innervating the cutaneous nerve were small (less than 300 microns 2). A total of 32% of the tooth pulp cells exhibited CA activity. CA-containing cells constituted only about 4% of the cutaneous nerve cells. In view of the known distribution of CA within the rodent nervous system, the CA-containing cells are considered to represent the tooth pulp primaries conducting in A-beta velocity range and projecting to rostral subdivisions of the brainstem sensory trigeminal nuclear complex.